A pressure-gradient-driven tokamak "resistive magnetohydrodynamic" instability in the banana-plateau collisionality regime

J. D. Callen, K. C. Shaing

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The moment equation approach to neoclassical processes is used to derive the linearized electrostatic perturbed flows, currents, and resistive MHD-like equations for a tokamak plasma. The new features of the resultant "neoclassical magnetohydrodynamics," which requires a multiple length scale analysis for the parallel eigenfunction, but is valid in the experimentally relevant banana-plateau regime of collisionality, are: (1) a global Ohm's law that includes a fluctuating bootstrap current resulting from the "parallel" electron viscous damping (at rate μe) of the poloidal flow due to the perturbed radial pressure gradient; (2) reduction of the curvature effects to their flux surface average because Pfirsch-Schlüter currents cancel out the lowest-order geodesic curvature effects: (3) an increased polarization drift contribution with B-2, replaced by B-2, where B is the poloidal magnetic field component. An electrostatic eigenmode equation is determined from ▽·J̃=0. For the unstable fluid-like eigenmodes, the new viscous damping effects dominate (by ε-3/2) over the curvature effects, but the growth rates still scale roughly like resistive-g or resistive-ballooning modes, γμτΑ∼ n2/3SN1/3βT2/3ee)1/3. Diamagnetic drift frequency corrections to these new modes are also discussed.

Original languageEnglish
Pages (from-to)1845-1858
Number of pages14
JournalPhysics of Fluids
Issue number6
Publication statusPublished - 1985 Jan 1


All Science Journal Classification (ASJC) codes

  • Computational Mechanics
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

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